CA2158914A1 - Electric sleeve heater with different-temperature heating zones - Google Patents
Electric sleeve heater with different-temperature heating zonesInfo
- Publication number
- CA2158914A1 CA2158914A1 CA002158914A CA2158914A CA2158914A1 CA 2158914 A1 CA2158914 A1 CA 2158914A1 CA 002158914 A CA002158914 A CA 002158914A CA 2158914 A CA2158914 A CA 2158914A CA 2158914 A1 CA2158914 A1 CA 2158914A1
- Authority
- CA
- Canada
- Prior art keywords
- electrical heater
- machine part
- wire
- groove
- heater defined
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 238000010438 heat treatment Methods 0.000 title claims abstract description 15
- 238000009413 insulation Methods 0.000 claims abstract description 12
- 239000011810 insulating material Substances 0.000 claims description 2
- 229910001369 Brass Inorganic materials 0.000 description 4
- 239000010951 brass Substances 0.000 description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
- 239000010949 copper Substances 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 3
- 229920005989 resin Polymers 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/40—Heating elements having the shape of rods or tubes
- H05B3/42—Heating elements having the shape of rods or tubes non-flexible
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C33/00—Moulds or cores; Details thereof or accessories therefor
- B29C33/02—Moulds or cores; Details thereof or accessories therefor with incorporated heating or cooling means
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/17—Component parts, details or accessories; Auxiliary operations
- B29C45/72—Heating or cooling
- B29C45/74—Heating or cooling of the injection unit
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C35/00—Heating, cooling or curing, e.g. crosslinking or vulcanising; Apparatus therefor
- B29C35/02—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould
- B29C2035/0211—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould resistance heating
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Resistance Heating (AREA)
Abstract
An electrical heater for heating a machine part having a substantially cylindrical surface has a cast metallic body having an inner surface and an outer surface one of which has a portion in direct contact with the surface of the machine part and another portion offset therefrom and forming a space therewith. A heating element imbedded in the body includes a resistive wire, a layer of insulation surrounding the wire, and a dimensionally stable jacket surrounding the insulation layer.
Description
ELECTRIC SLEEVE HEATER WITH DIFFERENT-TEMPERATURE HEATING ZONES
SPECIFICATION
FIELD OF THE INVENTION
The present invention relates to an electrical heater.
More particularly this invention concerns a sleeve or plug heat that is set in a hole or fitted around a machine part to heat it.
BACKGROUND OF THE INVENTION
A cylindrical electric heater, whether tubular so it can be slipped over a machine part to be heated or solid so it can be fitted into a hole in a machine part to be heated, typically has a cast metallic body having an inner surface and an outer surface, one of which is in direct contact with the surface of the machine part. A heating element, typically formed as a helical coil, is imbedded in the body and has a resistive wire, a layer of insulation surrounding the wire, and a dimensionally stable jacket surrounding the insulation layer. Electricity is passed through the wire to heat the element and the heat is transmitted through the copper or brass body to the machine part being heated.
Such a heater is normally of circular section. When used, for instance, to heat an injector nozzle it is tubular and 21S8gl~
is fitted over the cylindrical outer surface of the nozzle. In other systems it is solid and is fitted into a cylindrical bore in the part to be heated.
In many applications it is advantageous to heat different zones of the machine part to different temperatures.
This is typically done by varying the pitch of the heating element, making its pitch steeper in areas to be heated less and shallower where more heat is required. Since, however, the body is highly thermally conductive, such systems are only marginally effective because the heat from the element will flow rapidly in the brass or copper body.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to provide an improved electrical heater for a machine part.
Another object is the provision of such an improved electrical heater for a machine part which overcomes the above-given disadvantages, that is which can produce sharply different temperatures in different zones of the machine part it is being used to heat.
SUMMARY OF THE lNv~NllON
An electrical heater for heating a machine part having a substantially cylindrical surface has according to the invention a cast metallic body having an inner surface and an outer surface one of which has a portion in direct contact with the surface of the machine part and another portion offset therefrom and forming a space therewith. A heating element imbedded in the body includes a resistive wire, a layer of insulation surrounding the wire, and a d.mensionally stable jacket surrounding the insulation layer.
Thus with this system the actual heat transfer between the heated surface of the heater and the surface to be heated of the machine part is reduced. When the space is empty the heat exchange in the one surface portion is conductive and highly efficient while at the other surface portion is radiant and fairly inefficient. To further reduce heat exchange a mass of thermal-insulating material fills the space.
According to this invention the other surface portion is formed by a floor of an annular groove in the body. It can also be formed by an axial groove in the body. When the body is formed with two axially extending grooves defining respective such other surface portions and subdividing the body into two regions, each such portion can be provided with a respective such heating element.
215891~
19654 Li The element in accordance with this invention can be at least generally helical and can be of reduced pitch in the other surface portion to reduce the heat transmission in this zone even further. The body can be formed to each side of the groove with a radially projecting rib. A jacket is provided on the one surface of the body.
BRIEF DESCRIPTION OF THE DRAWING
The above and other objects, features, and advantages will become more readily apparent from the following description, it being understood that any feature described with reference to one embodiment of the invention can be used where poscible with any other embodiment and that reference numerals or letters not specifically mentioned with reference to one figure but identical to those of another refer to structure that is functionally if not structurally identical. In the accompanying drawing:
FIG. 1 is an end view of a heater according to the invention;
FIG. 2 is a section taken along line II--II of FIG. l;
FIG. 3 is an end view of another heater;
FIG. 4 is a section taken along line IV--IV of FIG. 3;
FIG. 5 is an end view of another heater:
FIG. 6 is a section taken along line VI--VI of FIG. 5;
FIG. 7 is an end view of another heater; and - 215891~
FIG. 8 is a section taken along line VIII--VIII of FIG.
7.
SPECIFIC DESCRIPTION
As seen in FIGS. 1 and 2 a sleeve heater 1 according to this invention is intended to fit around a cylindrical part 19, here an extruder nozzle, centered on an axis A. A resistive-type heating wire 2 is imbedded in insulation 3 and surrounded by a dimensionally stable metallic jacket 4. It is shaped into a helix with a small pitch at each end and a large pitch in a central region and is imbedded in a tubular body 5 of brass or copper. This assembly is surrounded by another jacket 7 here of stainless steel. A two-conductor cable 8 is connected to the wire 2 for passing an electric current through it and thereby generating heat that is transmitted to the cylindrical surface of the body 19.
According to the invention the heater 1 forms a passage 6 centered on the axis A and having cylindrical small-diameter end regions 9 where it directly contacts the outer surface of the machine part 19 to be heated, and a cylindrical central larger-diameter region 10 that is spaced from this part 19 and that isformed by the floor of a wide radially inwardly open annular groove. Insulation 18 may be provided in the region 10 to reduce heat transfer. Thus the part 19 will be heated substantially at zones corresponding to the direct-contact end regions 9, where ~; _ the wire 2 is wound in a tight helix, and is heated less in the central region where direct heat conduction is largely eliminated.
In the arrangement of FIGS. 3 and 4 the nondirect-contact region is formed by an axially extending inwardly opengroove 11 that is machined in the brass body 5. This system is handy for injector nozzles having passages for two different resins that need to be heated to different temperatures.
The arrangement of FIGS. 5 and 6 has two separate resistive wires 12 and 13 supplied by separate cables 14 and 15.
The body 5 is formed with two separate diametrically opposite, axially extending, and radially inwardly open grooves 11 that subdivide it into two sections 16 and 17. The wire 12 runs only in the section 16 and the wire 13 only in the section 17 and the floors of the grooves 11 form noncontact regions that thermally separate the sections 16 and 17.
A similar system is shown in FIGS. 7 and 8, but here the body 5 is formed to each side of each notch 11 with a radially inwardly projecting pointed ridge S' that engages in a respective slot of the unillustrated machine part being heated.
As in FIGS. 5 and 6, this arrangement is ideal for a nozzle that has separate passages for resins needing to be heated to different temperatures.
SPECIFICATION
FIELD OF THE INVENTION
The present invention relates to an electrical heater.
More particularly this invention concerns a sleeve or plug heat that is set in a hole or fitted around a machine part to heat it.
BACKGROUND OF THE INVENTION
A cylindrical electric heater, whether tubular so it can be slipped over a machine part to be heated or solid so it can be fitted into a hole in a machine part to be heated, typically has a cast metallic body having an inner surface and an outer surface, one of which is in direct contact with the surface of the machine part. A heating element, typically formed as a helical coil, is imbedded in the body and has a resistive wire, a layer of insulation surrounding the wire, and a dimensionally stable jacket surrounding the insulation layer. Electricity is passed through the wire to heat the element and the heat is transmitted through the copper or brass body to the machine part being heated.
Such a heater is normally of circular section. When used, for instance, to heat an injector nozzle it is tubular and 21S8gl~
is fitted over the cylindrical outer surface of the nozzle. In other systems it is solid and is fitted into a cylindrical bore in the part to be heated.
In many applications it is advantageous to heat different zones of the machine part to different temperatures.
This is typically done by varying the pitch of the heating element, making its pitch steeper in areas to be heated less and shallower where more heat is required. Since, however, the body is highly thermally conductive, such systems are only marginally effective because the heat from the element will flow rapidly in the brass or copper body.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to provide an improved electrical heater for a machine part.
Another object is the provision of such an improved electrical heater for a machine part which overcomes the above-given disadvantages, that is which can produce sharply different temperatures in different zones of the machine part it is being used to heat.
SUMMARY OF THE lNv~NllON
An electrical heater for heating a machine part having a substantially cylindrical surface has according to the invention a cast metallic body having an inner surface and an outer surface one of which has a portion in direct contact with the surface of the machine part and another portion offset therefrom and forming a space therewith. A heating element imbedded in the body includes a resistive wire, a layer of insulation surrounding the wire, and a d.mensionally stable jacket surrounding the insulation layer.
Thus with this system the actual heat transfer between the heated surface of the heater and the surface to be heated of the machine part is reduced. When the space is empty the heat exchange in the one surface portion is conductive and highly efficient while at the other surface portion is radiant and fairly inefficient. To further reduce heat exchange a mass of thermal-insulating material fills the space.
According to this invention the other surface portion is formed by a floor of an annular groove in the body. It can also be formed by an axial groove in the body. When the body is formed with two axially extending grooves defining respective such other surface portions and subdividing the body into two regions, each such portion can be provided with a respective such heating element.
215891~
19654 Li The element in accordance with this invention can be at least generally helical and can be of reduced pitch in the other surface portion to reduce the heat transmission in this zone even further. The body can be formed to each side of the groove with a radially projecting rib. A jacket is provided on the one surface of the body.
BRIEF DESCRIPTION OF THE DRAWING
The above and other objects, features, and advantages will become more readily apparent from the following description, it being understood that any feature described with reference to one embodiment of the invention can be used where poscible with any other embodiment and that reference numerals or letters not specifically mentioned with reference to one figure but identical to those of another refer to structure that is functionally if not structurally identical. In the accompanying drawing:
FIG. 1 is an end view of a heater according to the invention;
FIG. 2 is a section taken along line II--II of FIG. l;
FIG. 3 is an end view of another heater;
FIG. 4 is a section taken along line IV--IV of FIG. 3;
FIG. 5 is an end view of another heater:
FIG. 6 is a section taken along line VI--VI of FIG. 5;
FIG. 7 is an end view of another heater; and - 215891~
FIG. 8 is a section taken along line VIII--VIII of FIG.
7.
SPECIFIC DESCRIPTION
As seen in FIGS. 1 and 2 a sleeve heater 1 according to this invention is intended to fit around a cylindrical part 19, here an extruder nozzle, centered on an axis A. A resistive-type heating wire 2 is imbedded in insulation 3 and surrounded by a dimensionally stable metallic jacket 4. It is shaped into a helix with a small pitch at each end and a large pitch in a central region and is imbedded in a tubular body 5 of brass or copper. This assembly is surrounded by another jacket 7 here of stainless steel. A two-conductor cable 8 is connected to the wire 2 for passing an electric current through it and thereby generating heat that is transmitted to the cylindrical surface of the body 19.
According to the invention the heater 1 forms a passage 6 centered on the axis A and having cylindrical small-diameter end regions 9 where it directly contacts the outer surface of the machine part 19 to be heated, and a cylindrical central larger-diameter region 10 that is spaced from this part 19 and that isformed by the floor of a wide radially inwardly open annular groove. Insulation 18 may be provided in the region 10 to reduce heat transfer. Thus the part 19 will be heated substantially at zones corresponding to the direct-contact end regions 9, where ~; _ the wire 2 is wound in a tight helix, and is heated less in the central region where direct heat conduction is largely eliminated.
In the arrangement of FIGS. 3 and 4 the nondirect-contact region is formed by an axially extending inwardly opengroove 11 that is machined in the brass body 5. This system is handy for injector nozzles having passages for two different resins that need to be heated to different temperatures.
The arrangement of FIGS. 5 and 6 has two separate resistive wires 12 and 13 supplied by separate cables 14 and 15.
The body 5 is formed with two separate diametrically opposite, axially extending, and radially inwardly open grooves 11 that subdivide it into two sections 16 and 17. The wire 12 runs only in the section 16 and the wire 13 only in the section 17 and the floors of the grooves 11 form noncontact regions that thermally separate the sections 16 and 17.
A similar system is shown in FIGS. 7 and 8, but here the body 5 is formed to each side of each notch 11 with a radially inwardly projecting pointed ridge S' that engages in a respective slot of the unillustrated machine part being heated.
As in FIGS. 5 and 6, this arrangement is ideal for a nozzle that has separate passages for resins needing to be heated to different temperatures.
Claims (10)
1. An electrical heater for heating a machine part having a substantially cylindrical surface, the heater comprising:
a cast metallic body having an inner surface and an outer surface, one of the surfaces of the body having a portion in direct contact with the surface of the machine part and another portion offset therefrom and forming a space therewith;
and a heating element imbedded in the body and including a resistive wire, a layer of insulation surrounding the wire, and a dimensionally stable jacket surrounding the insulation layer.
a cast metallic body having an inner surface and an outer surface, one of the surfaces of the body having a portion in direct contact with the surface of the machine part and another portion offset therefrom and forming a space therewith;
and a heating element imbedded in the body and including a resistive wire, a layer of insulation surrounding the wire, and a dimensionally stable jacket surrounding the insulation layer.
2. The electrical heater defined in claim 1, further comprising a mass of insulating material filling the space.
3. The electrical heater defined in claim 1 wherein the other surface portion is formed by an annular groove in the body.
4. The electrical heater defined in claim 1 wherein the other surface portion is formed by an axial groove in the body.
5. The electrical heater defined in claim 1 wherein the body is formed with two axially extending grooves defining respective such other surface portions and subdividing the body into two regions each provided with a respective such heating element.
6. The electrical heater defined in claim 1 wherein the element is at least generally helical.
7. The electrical heater defined in claim 1 wherein the body is formed with at least one axially extending groove having a floor constituting the other surface portion.
8. The electrical heater defined in claim 7 wherein the body is formed to each side of the groove with a radially projecting rib.
9. The electrical heater defined in claim 1 further comprising a jacket on the one surface of the body.
10. An electrical heater for heating a machine part having a substantially cylindrical outer surface, the heater comprising:
a cast metallic body having a cylindrical inner surface in direct contact with the surface of the machine part and formed with a groove having a floor defining a surface portion offset from the machine-part surface and forming a space therewith; and a nonstraight heating element imbedded in the body and including a resistive wire, a layer of insulation surrounding the wire, and a dimensionally stable jacket surrounding the insulation layer.
a cast metallic body having a cylindrical inner surface in direct contact with the surface of the machine part and formed with a groove having a floor defining a surface portion offset from the machine-part surface and forming a space therewith; and a nonstraight heating element imbedded in the body and including a resistive wire, a layer of insulation surrounding the wire, and a dimensionally stable jacket surrounding the insulation layer.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP4434017.6-34 | 1994-09-23 | ||
| DE4434017 | 1994-09-23 | ||
| DEP4445744.8-34 | 1994-12-21 | ||
| DE4445744A DE4445744C1 (en) | 1994-09-23 | 1994-12-21 | Electrical heating element esp. for injection moulding or spray moulding machine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2158914A1 true CA2158914A1 (en) | 1996-03-24 |
Family
ID=25940414
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002158914A Abandoned CA2158914A1 (en) | 1994-09-23 | 1995-09-22 | Electric sleeve heater with different-temperature heating zones |
Country Status (3)
| Country | Link |
|---|---|
| CA (1) | CA2158914A1 (en) |
| FR (1) | FR2725105B1 (en) |
| IT (1) | IT1274519B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113864559A (en) * | 2021-09-28 | 2021-12-31 | 临海伟星新型建材有限公司 | Electric melting pipe fitting with blocking function and manufacturing method thereof |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3915041B2 (en) * | 1995-11-08 | 2007-05-16 | ホツトセツト・ハイツパトローネン・ウント・ツーベヘール・ゲゼルシヤフト・ミツト・ベシユレンクテル・ハフツング | Electric heating element for injection molding tools |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2340965A1 (en) * | 1973-08-13 | 1975-02-27 | Behr Thomson Dehnstoffregler | Electric heater mounting for cylindrical part - mounted on elastic ring round part to be heated |
| US4558210A (en) * | 1984-08-03 | 1985-12-10 | Watlow Electric Manufacturing Company | Electric cast-metal heater |
| US5360333A (en) * | 1992-09-30 | 1994-11-01 | Husky Injection Molding Systems Ltd. | Band heater clamp arrangement for an injection molding machine |
-
1995
- 1995-05-17 IT ITMI951002A patent/IT1274519B/en active IP Right Grant
- 1995-05-26 FR FR9506551A patent/FR2725105B1/en not_active Expired - Fee Related
- 1995-09-22 CA CA002158914A patent/CA2158914A1/en not_active Abandoned
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113864559A (en) * | 2021-09-28 | 2021-12-31 | 临海伟星新型建材有限公司 | Electric melting pipe fitting with blocking function and manufacturing method thereof |
| CN113864559B (en) * | 2021-09-28 | 2023-05-12 | 临海伟星新型建材有限公司 | Electric smelting pipe fitting with barrier function and manufacturing method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| ITMI951002A0 (en) | 1995-05-17 |
| FR2725105A1 (en) | 1996-03-29 |
| IT1274519B (en) | 1997-07-17 |
| FR2725105B1 (en) | 1997-07-18 |
| ITMI951002A1 (en) | 1996-11-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |